Ventilation is important in livestock barns in general and hog barns in particular. Attic inlets allow air to exchange between the attic space of a barn above a ceiling, usually to provide an intermediate temperature acting as a buffer, between the barn interior and the outside.
Attic inlets are generally rectangular housings with a lid or lids which can be closed preventing air interchange between attic and barn interior or open allowing air interchange. Typically there are a plurality of inlets with lids all controlled from a central point, which open together to the same extent. The inlet housing is typically a short rectangular or square tube set in the barn ceiling, with a lid or lids which can be opened. In one form there is a fixed panel transverse to the tube, and louvers set in opposed sides of the tube, sometimes all four sides.
Canadian Patent Application 2,763,969 and US Patent Application Publication 20120178356 both published 12 Jul. 2012 to applicant, teach a rectangular inlet, differing from instant invention, where the lid is moved by an upper pull bar and lower connecting bars attached to the lid. Upper pull bar and lower connecting bars are attached by clevis pins to yoke arms pivoting about parallel axles. Movement of the upper pull bar rotates the yoke arms, and so lowers the connecting bars and the attached lid. Springs urge pull bar and lid into closed default position, while a cord is used to displace pull bar and lid into open position. The lid is attached by tabs on the connecting bars passing through the lid, and lid locking bars engaging apertures in the tabs.
U.S. Pat. No. 6,475,078, to Borcherding, 5 Nov. 2002, teaches such a device, which has counterweighted louvers which are opened by air pressure to provide air exchange, a shutoff louver is also provided. In another form the lid(s) are transverse to the tube axis. A single lid may be hinged or pivoted on one side, in which case it is lowered to open position to allow air exchange. Double lids may be pivoted centrally and lowered to provide air exchange, alternatively they may be pivoted at their outer edges and lowered to provide air exchange. In another form the lid may be lowered horizontally to provide air exchange.
A particular one lid four way inlet, is the counterweighted Eagan Sturdy Seal, for which, although extensively advertised, no clear diagram, picture or photograph is available. The lid is lowered horizontally by a scissors frame arrangement, the counterweight urges the lid closed, while the cable, cord, string, wire, or the like moves the counterweight allowing the lid to open. This has the advantage over other systems that the counterweight is used to hold the lid closed, while the cable, cord, string, wire or the like, opens the lid, when pulled by a machine. In most inlets the machine pulls the lid closed, as the strings stretch, unless the inlet strings are perfectly adjusted, individual inlets may stay open.
Typically the lid is controlled by a cable, cord, string, wire or the like, which may open the lid or close the lid, the default position is closed. Counterweights or springs can be used to either urge the lid closed or open. Lids may have manual shutoffs as well. In general since the ventilation is effected by fans, the lids default position is shut when the fans are off. Cables, cords, strings, wires and the like stretch in use, so springs or counterweights are preferably used to keep the lid(s) shut when not in use. The cable, cord, string or wire and the like is then used to open the lid(s) against counterweight or spring. It is preferred that the cable, cord, string, wire and the like be machine controlled, and more preferably that one machine control all the air inlet lids in a building, so that they can be actuated together.